This invention relates generally to a method of controlling parasites and formulating and applying topical formulations that can have significant parasiticidal or anti-parasite activity, such as one suitable to use on house pets such as dogs and cats.
The infestation of companion animals with fleas, ticks, and the like is highly undesirable and as such, it is beneficial to develop improved products to fight such infestation. Topical applications can be desirable since many formulations are acceptably safe when used topically, even if not when used internally.
Topical applications are more advantageous if the amount of liquid applied to the animal can be minimized. This should be balanced with the need for appropriate dosage to achieve the desired pesticidal effect. Therefore, it is desirable to use highly active insecticide so that the total volume of the insecticide applied to the animal can be minimized.
Topical applications often contain an insect growth regulator (IGR) component. IGRs kill flea larvae and prevent flea eggs from hatching. Such formulations provide for an effective flea control system since only about 5% of the existing fleas on an animal can be adults and the other 95% in a juvenile state (eggs and larvae). For example, methoprene, hydroprene and pyriproxyfen (commercially available as Nylar) are IGRs that prevent flea eggs from hatching.
However, it has been determined that various IGR containing formulations have drawbacks due the characteristics of the chosen IGR. For some IGRs, it is difficult to maintain an effective concentration at the affected area of the animal and requires that a large volume to be applied. For other IGRs, it is difficult to provide sufficient coverage surrounding the treatment area, thereby permitting parasites to persist in other areas of the animal or in the environment such as pet bedding, carpeting, upholstery, and so forth. Again, a large volume is required to provide coverage.
This can cause considerable mess and can lead to an unpleasant smell. Additionally, if the dosage of a topical formulation is in a large volume, it can be easily shaken off by the animal thereby reducing the effectiveness of the formulation. Furthermore, when the animal is a house pet, there is a further complication in that the formulation should be safe for human contact. A large dose of an IGR may lead to staining of furniture, carpeting and the like. Finally, even if safe, topical formulations should not be irritating or lead to rashes, hair loss or exhibit other unpleasant side effects.
Accordingly, it is desirable to develop improved formulations.